Tuesday 30 March 2010 17.28 EDT
First published on Tuesday 30 March 2010 17.28 EDT

Russian investigators warned of further possible attacks following Monday's deadly bombings on the Moscow metro and said a squad of up to 20 trained suicide bombers was still at large.

The federal security service (FSB) said the two women who blew themselves up during the morning rush hour may have been members of a larger, 30-strong group of suicide bombers recruited and trained by Chechen rebel leader, Said Buryatsky.

Buryatsky was an influential Islamic convert and ideologue who posted jihadist video messages on YouTube. Special forces killed him earlier this month. Investigators are examining whether the bombings at Lubyanka and Park Kultury metro stations – in which 39 people died – may have been in retaliation for his death.

Russians observed a day of mourning today, with Muscovites laying flowers and lighting candles at the scene of the explosions. The death toll rose to 39 after a young woman injured in the blasts died overnight. More than 70 people were still being treated in hospitals.

The Kremlin signalled it is planning a tough response. Prime minister Vladimir Putin said the culprits should be "scraped from the bottom of the sewers" – a phrase reminiscent of his 1999 promise that he would "rub out" Chechen rebels "even in the outhouse".

Investigators today said the two young women bombers arrived in Moscow's Luzhniki market at dawn on Monday after travelling on an intercity bus from a town in the north Caucasus. A stocky man, 180-185cms tall, wearing a dark blue jacket with white insets, accompanied them. They had three bags of luggage.

According to the Russian news agency Interfax, the women soon afterwards boarded the metro at Vorobyovy Gory or Sparrow Hills, a scenic metro station directly overlooking the Moscow river and university. The pair then travelled together into the centre of town.

Kommersant newspaper, quoting investigators, said Buryatsky may have recruited a group of potential suicide bombers and dispatched them to a mosque in Turkey. After receiving training the group returned to Russia. Nine out of 30 recruits had already blown themselves up. But the other 21 had not been found, the paper said. Law enforcement officers were today urgently tracing female relatives of rebel leaders killed in clashes with pro-government security forces, in an attempt to identify the bombers. Six locals sheltering Buryatsky died along with him during the 2-3 March operation in the Ingush village of Ekashevo.

Video images of two other woman accomplices and the man who travelled with them were also distributed today by police. The women, who were of Slavic appearance, guided the bombers into the metro system and appear to have led them to their targets.

According to Kommersant, the authorities may have been warned in advance about a possible suicide attack on the Moscow metro. Citing police sources, the paper said "three encoded telegrams" were circulated among law enforcement agencies before Monday's blasts.

The warning said "Chechen terrorists" were planning explosions on "transport objects" in Moscow, Kommersant reported. The newspaper also cited a woman from the north Caucasus – unconnected with the bombings – who was arrested on the platform of Okhotny Ryad station at 7.40am, minutes before the first bomb went off. The station is next to Lubyanka, where the FSB has its headquarters, on the same line.

The woman said she was taken to a police room in the station. As her documents and Moscow residence permit were checked the first explosion took place. A senior officer arrived minutes later, and shouted at his colleagues from the doorway: "How could you let them [the suicide bombers] through, when we had the information?"

There was criticism today of Russia's law enforcement agents. "They were too busy with corruption and intrigues to do their job," Alexander Khinshtein, a celebrity journalist writing in the best-selling Moskovsky Komsomolets said. Others lambasted Russia's state-controlled federal TV stations, which ignored the bombings for hours while awaiting Kremlin orders.

Today Tanya Lokshina, of Human Rights Watch's Moscow office, said it was too early to make any "definite conclusions" over who had carried out Monday's attacks. But she acknowledged that the bombings were probably linked to the pan-Caucasian insurgency in the republics of Chechnya, Ingushetia and Dagestan.

Lokshina said Putin's pledge to eliminate the terrorists was unlikely to solve the insurgency, which continued despite two Kremlin wars in Chechnya. "Eliminating human rights abuses [by pro-government forces] has to be a priority if the Russian authorities really want to improve the situation," she said.

She added: "The rhetoric of eliminating terrorists is flawed. In order to find out how these terrorist networks operate you need to need to identify the perpetrators, rather than shoot them, and bring them to justice. That's how you find out information."